This invention relates generally to intravascular insertion apparatus and methods and more particularly, but not by way of limitation, to an apparatus and a method for facilitating the insertion of intravascular catheters.
In anesthesiology and other medical areas it is often necessary to insert catheters into vessels within a body for either introducing substances into or extracting substances from such vessels. To properly insert a catheter into a vessel, the skin and subcutaneous tissue overlying and surrounding the vessel and the wall of the vessel itself must be pierced. Once these have been pierced, the catheter is placed within the lumen, or inner open space, of the vessel.
Although this insertion procedure seems simple, in practice it is difficult to pierce the skin, the subcutaneous tissue, and the vessel wall and ensure that the piercing ceases in the lumen so that the catheter can be properly moved into the lumen. For example, it is easy to pierce not only the near wall of the vessel but also the far wall, thereby preventing proper positioning of the catheter. Also, it is easy to only slightly pierce the near wall of the vessel so that the insertion of the catheter is made difficult. Therefore, there is the need for a device and a method for facilitating the insertion of intravascular catheters in such a manner that the chances of improperly piercing the vessel are reduced if not totally eliminated.
A current technique employed in the insertion of intravascular catheters utilizes a Teflon catheter which is seated on a steel needle forming a part of a syringe. The party who is to perform the catheter insertion grasps the patient's arm with his or her non-dominant hand (i.e., the hand not holding the catheter insertion device) and fixes the skin overlying the subcutaneous tissue and the vessel with his or her non-dominant thumb. By fixing the skin overlying the subcutaneous tissue and vessel, the relationship between these structures remains constant.
Having properly prepared the patient's arm, the party who is to insert the catheter holds the syringe-catheter assembly in his or her dominant hand (i.e., the hand other than the non-dominant hand). The dominant hand moves the syringe-catheter assembly into engagement with the patient's arm so that the needle pierces the skin and tissue overlying the vessel and enters the vessel. Applying constant suction with the syringe, the vessel is located with the return of blood into the syringe.
Upon noting that the vessel has been located, the catheter inserter attempts to pass the catheter into the vessel. At this point, however, the tip of the needle may have pierced both the near wall and the far wall of the vessel or, on the other hand, it may have only barely pierced the near wall of the vessel and thus may not be centered in the vessel. If the needle is in either of these non-centered positions, the attempt to pass the catheter into the vessel will be unsuccessful and the procedure will need to be performed again at a different site.
Besides this shortcoming of the current technique whereby the needle may not be properly centered, this procedure also has the shortcoming of requiring either the dominant hand or the nondominant hand to be moved to the catheter to push the catheter off the needle and into the vessel. This movement of either the dominant hand or the non-dominant hand prior to a definite mechanical link (such as by a guide element) being made with the lumen of the vessel increases the risk of movement of the needle relative to the vessel and the subsequent failure to maintain the catheter properly positioned within the vessel.
To assist in properly locating the lumen of the vessel and establishing a mechanical link therewith for guiding the catheter into the lumen, another current technique has utilized a separate guide wire which is to be moved into the vessel after the vessel has been located and the syringe body has been removed from the syringe needle. Once the syringe body has been removed, the guide wire which is separate from the syringe and catheter assembly is then passed through the needle and into the vessel whereupon the catheter can be passed over the guide wire and into proper position within the vessel.
This latter technique also has shortcomings. For example, the guide wire must be handled in a sterile manner to prevent the introduction of infection into the vessel; however, this is difficult because the guide wire is a separate unit and must be directly handled by the catheter inserter. To ensure the sterility of the guide wire, therefore, the inserter must sterilize the area where the catheter is to be inserted and the inserter must also wear sterile gloves. Both of these preparations are so time consuming and costly that they are usually not made until a troublesome insertion is encountered at which time it is usually too late to rectify the problem.
Another shortcoming of this latter technique is that the separation of the syringe body from the syringe needle and the insertion of the guide wire into the syringe needle requires that one or both hands be removed from their original positions. This increases the probability of movement of the needle with respect to the vessel prior to the time the guide wire can be inserted into the syringe needle.
In view of the foregoing shortcomings, there is the need for an improved intravascular insertion apparatus and method for readily locating the lumen of a vessel and for properly guiding a catheter into the lumen once it is located. This need requires the utilization of a sterile guide mechanism constructed to obviate the necessity of directly handling the guide mechanism during its use and further constructed to be moved by the same hand which holds the insertion device to obviate the necessity of removing one or both of the hands from their original positions prior to the time an adequate mechanical link can be made with the vessel.
So that the insertion device can indicate when a vessel has been located by displaying a quantity of blood flowing from the vessel, the insertion device also needs a chamber for receiving vascular fluid, such as blood, to detect when the insertion device is in the vessel. This chamber must be open to the flow of fluid from the vessel, but it also must be maintained sterile to prevent infection.
Because catheters often need to be inserted into vessels having low pressure, it is also necessary for the insertion device to include means for applying a suction to the fluid-receiving chamber to assist the extraction of a fluid from a vessel when the fluid pressure within the vessel is relatively low.